Evolution of Genome in Near-Real Time

"Paleontologists look at the fossil record to study how evolution of dinosaurs and other animals occurred over millions of years, but in the case of the E. coli bacterium, new technology has given us the ability to observe evolution as it is occurring over a matter of days," said Bernhard Ø. Palsson, professor of bioengineering at UCSD. "The published genomic sequences of bacteria are like a fossil record and our experiments confirm that these genomes can change quickly as bacteria adapt to new conditions."

Palsson's team used comparative genome sequencing technology to identify evolutionary changes that occurred during the experiment in the bacterium's complete set of genes.

The researchers report that they grew E. coli in an environment that favored the emergence of mutants: the organism was fed a poorly metabolized carbon and energy source called glycerol.

After six days of growth, mutations appeared in the gene for an enzyme that initiates the process of enzymatically breaking down glycerol. Cells with mutations in the so-called glycerol kinase gene grew 20 to 60 percent faster than those without the mutation.

"This straightforward approach to the study of experimental evolution can be used as a tool for discovery and analysis, and could even be used to discover bacterial capabilities that would benefit humankind in a variety of ways," said Herring.